You can certainly try walking in but chances are slim at best. Better chance to ask to be on the wait list if the restaurant has that policy. If not, call periodically to check if there is a cancellation. Chances for a cancellation are good. Try lunch as it is usually not fully booked. Food and menu are no different between lunch and dinner. That is about all one can do.

When we were at GRESCA, I saw a walk-in couple beg to get a table for early dinner (we were the only diners at the time). No deal. Some of these restaurants are very small by American standards and they will actually call you - more than once - just to make sure you are really coming for dinner!

"they will actually call you - more than once - just to make sure you are really coming for dinner!"

Quite a common thing here in the UK for higher end places to phone to check you're going, even when they've taken a credit card reservation and are going to make a "no show" charge if you don't. Presumably all about giving them the best chance to resell the table. Never had it happen with places overseas though.

We've done that and have been lucky to get seated when we did the walk-in thing at high end restaurants. One of them, Akelare, in SS sat us at what was most likely the worst table in the restaurant but it turned out to be one of the best meals we've ever had.